1. Priority Claim
This application claims priority to Taiwanese Patent Application No. 098106258 filed on Feb. 26, 2009.
2. Field of the Invention
The present invention relates to a display device using a surface capacitive touch panel and its related method, more particularly, to a power-down display device using a surface capacitive touch panel device and its drive method.
3. Description of Prior Art
With a rapid development of monitor types, novel and colorful monitors with high resolution, e.g., liquid crystal displays (LCDs), are indispensable components used in various electronic products such as monitors for notebook computers, personal digital assistants (PDAs), digital cameras, and projectors. The demand for the novelty and colorful monitors has increased tremendously.
Nowadays, in order to carry and use liquid crystal displays more easily, developing a touch liquid crystal panel that users can touch directly also becomes one of the tendencies of market development. Conventional optical touch panels set up a quantity of light and its corresponding optical sensing elements around the liquid crystal panel, utilizing the optical sensing elements to detect the light corresponded to its optical source to judge position coordinates of points of contact pressure. Such a design will increase the volume of the products by a large margin, so this design does not meet the requirements of general portable liquid crystal displays. Another kind of touch panel device is a surface resistance touch display panel or a surface capacitive touch display panel, which is placed additionally on display panels, such as LCD panels and CRT displays, and is judged its position coordinates by detecting variations of voltage values of points of contact pressure. However, because a touch panel is directly placed on a display panel, the rate of penetration of light will decline.
Referring to FIG. 1 showing a block diagram of a conventional display device 10 using a surface capacitive touch panel, the display device 10 comprises a clock generator 1, a surface capacitive touch panel 6, and a touch panel controller 8. The touch panel controller 8 integrates and comprises a phase lack loop (PLL) 2, a control logic 7, a signal generator 4, and a current detector 5. The clock generator 1 can be a crystal oscillator. The clock generator 1 is used as an external clock generator to generate clock signals to other circuits. When the surface capacitive touch panel 6 is enabled, the signal generator 4 will generate sensing signals to detect whether a user's fingers touch the surface capacitive touch panel 6 or not. Meanwhile, the current detector 5 will detect currents in response to a contact of the user's fingers on the surface capacitive touch panel 6. The control logic 7, comprising the interface controller 3, can determine the fingers' touch positions on the surface capacitive touch panel 6 according to the sensing current detected by the current detector 5, and then transmit the touch positions to the host for the use of the system. Once the display device 10 is enabled, the circuits of the display device 10 will always remain functioning in order to detect all the time whether a user's fingers touch the surface capacitive touch panel 6 or not. Practically, however, the surface capacitive touch panel 6 is not always enabled. For most of time, it will squander power additionally to keep all of the circuits functioning. Based upon the consideration above, developers make every effort to manufacture a power-down surface capacitive touch panel to correspond with the more eco-friendly era.